Mitchell attended Covington Catholic High School in Park Hills, Kentucky for his first three years. He lettered as a sophomore and junior before transferring to Highlands High School in Fort Thomas, Ky., where he lettered one, and earned Kentucky All-Star honors, in addition to being selected honorable mention All-State as a senior. That year, he led the team to the state title, recording 87 tackles with three forced fumbles and two fumble recoveries, returning one for a touchdown.

Mitchell would begin attending Ohio University in 2005 to play football for first year coach Frank Solich. He would begin the season on the bench but would eventually earn his first career start the second game against Pittsburgh. On October 8, he would make his first tackle in a game against Bowling Green and end the game with 5 altogether and one for a loss. Ohio would play Toledo in week 10 and Mitchell would rack up a career-high 8 tackles and force a fumble. He would finish his freshman season with a total of 21 tackles, 2 pass deflections, and a forced fumble for a Ohio team that would end the season at 4-7. [1]

He would return in 2006 for his second season and begin the season as a back-up but would play in all 14 games. For week 6, Ohio would play Western Michigan and Mitchell would record a season-high 7 tackles in the 27-20 victory. The next week he would receive his first start at free safety against Illinois and would maintain the starting role the next 7 games. In a week 10 matchup against Eastern Michigan, he would make his first career interception in the fourth quarter that would lead to the game-winning touchdown. The Bobcats would play Central Michigan in the MAC Championship, with Mitchell shifting over to strong safety and ending the game with 6 tackles and an interception. After losing to Southern Mississippi, Mitchell would end his season with 55 tackles, 5 tackles for a loss, 1 sack, 2 interceptions, and a forced fumble. [1]

After a season where the bobcats would end with a 9-5 record, Mitchell would return as the Bobcats starting strong safety, despite having many injuries. During a week 4 contest with Wyoming, he would amass a career-high 14 tackles and 2 interceptions. The next game, Mitchell would assist 7 tackles and have 1.5 tackles for loss against Kent State. He would end the season with a career-high 74 tackles, 4 tackles for loss, 1.5 sacks, 2 interceptions, and a team-high 47 solo tackles. [1]

For his final year Mitchell would start 11 games at strong safety for the Bobcats. During a week 4 contest at Northwestern, he would pick off 2 passes in a 8-16 loss. While playing against VMI, he would make 4.5 tackles for a loss and 2 forces fumbles. After sitting out week 11 against Bowling Green with an injury, he would return the next game against Akron, Mitchell to make 9 tackles in the 49-42 victory. He would finish his senior campaign with 62 tackles and lead the team with 3 interceptions.

Mitchell started 30 of 45 games at Ohio University--23 at strong safety and seven at free safety. He would end his career at Ohio with a total of 213 tackles, 126 solo, 14.5 tackles for loss, 3 sacks, 5 forced fumbles, and 7 interceptions for 140 return yards. [1]

Mitchell wasn't invited to the NFL Combine, but performed well at Ohio's Pro Day. He ran a 4.39-second 40-yard dash and he did 22 repetitions of 225 pounds on the bench press to go along with a 37½-inch vertical and a 10-foot, 3-inch broad jump.

Mitchell's selection raised eyebrows on draft day, as most television commentators had never heard of him and could not find him in draft guides. Mitchell was generally expected to be a second-day pick or an undrafted free agent.[3][4]ESPN analyst Mel Kiper said Mitchell's grade was somewhere between the 40th and 70th safety available in the draft, and the NFL Network's Mike Mayock had given Mitchell a seventh round grade.[5] But after posting a 4.43 time in the 40-yard dash at Ohio University's pro day, he was selected by the Oakland Raiders with the 47th overall selection. Later on draft day, it was reported that Mitchell was being targeted by the Chicago Bears (selecting at 49—two spots behind the Raiders).[6] However, after Mitchell was taken by the Raiders, the Bears ultimately traded their selection. Upon report of this, Mike Mayock of the NFL Network apologized to the Raiders for his low grade.[7]Mel Kiper later gave it "Most Likely To Make The Raiders Look Good Award," stating "Oakland took Michael Mitchell, OK?" "I asked teams after the draft. The misnomer is it's all Mel Kiper's opinion, it's all Todd McShay. You have to ask other teams. We're not the end-all, be-all. Some said they had him as a free agent. One team told me they had Michael Mitchell in the third round. They had him as a Pro Bowler. They think it's a great pick by the Oakland Raiders. So Oakland wasn't the only team out on the island that saw something in that kid."[8]

Mitchell is the highest Ohio player to be drafted since Gene Ruskowski's fifth-round selection (44th overall) by the Los Angeles Rams in 1948. The last time an Ohio student-athlete was drafted in a higher round was the Bobcats' only first round selection, Art Lewis (ninth overall) in 1936 by the New York Giants.[9]

Mitchell signed a one-year deal with the Carolina Panthers on March 20, 2013.[10] During the 2013-2014 season, he had a career year, recording his most sacks in a season with 3.5, most forced fumbles in a season with 2 and most interceptions in a season with 4.[11] His play contributed to a season where the defense was ranked 2nd in the NFL in total yards, rushing yards, and points, and helped the team win a division title and playoff berth for the first time in 5 years.[12][13]